Hard disk drives (HDDs) are used extensively in modem data processing systems for nonvolatile data storage. A typical HDD design consists of a spindle which holds one or more flat circular storage disks (also called platters). Each storage disk is made from a non-magnetic material, usually glass or aluminum, and is coated with a thin layer of magnetic material. Data is written to and read from the storage disk by spinning it at high speed and using a read/write (r/w) head to detect and modify the magnetization of the magnetic material on the surface of the storage disk immediately underneath the r/w head. An actuator arm precisely moves the r/w head on an arc across the storage disk as it spins, allowing the head to access almost the entire surface of the storage disk.
Unfortunately, in large part due to their moving parts, conventional HDDs typically consume a relatively large amount power when compared to other components in data processing systems. In portable data processing systems that utilize batteries, such as laptop computers, this frequently results in short battery durations. As a result, there have been several approaches to reducing power consumption in HDDs. One approach, for example, is to simply power down an HDD whenever immediate access to its stored data is not anticipated. Another approach is to reduce the power consumption of the HDD's electromechanical components by using, for example, full step-per-track actuators to move the r/w heads and low torque spindle motors to spin the storage disks. Nevertheless, these approaches usually have negative performance and reliability consequences. Powering down an HDD may lead to delayed data access times. Using lower power electromechanical components may result in reduced drive life.
As a result, there remains a need for novel HDD designs that provide reduced power consumption characteristics when compared to conventional HDD designs without substantially detracting from HDD performance and reliability.